Research On Preparation Of Mesoporous Silica-supported Metallic Phosphides And Hydrolytic Dehydrogenation Of Sodium Borohydride And Ammonia Borane

With the depletion of non-renewable resources such as oil,natural gas,and fossil fuels and the use of the above-mentioned energy sources is inevitable to bring a large number of toxic emissions will cause environmental pollution.Meantime,it is urgent for humans to find a clean and green new energy source to solve this problem.As a secondary energy source,hydrogen has high energy density and combustion heat value,and the product after combustion oxidation is water,clean and pollution-free,and is considered to be the cleanest energy source.Among the chemical hydrogen storage materials,ammonia borane and sodium borohydride have attracted wide attention of researchers due to their high hydrogen content,high efficiency and safety,and environmental friendliness.In the process of catalyzing the chemical hydrogen storage material ammonia borane and sodium borohydride dehydrogenation,it is essential to find a highly efficient and economical catalyst.In this paper,metal phosphide is selected as the active substance,and the metal phosphide is supported on the mesoporous spherical material SBA-15 in order to increase the dispersibility of the catalyst and reduce the agglomeration and improve the catalytic effect.The research content of this paper is as follows:（1）The spherical ordered mesoporous material SBA-15 was prepared by using the amphiphilic nonionic surfactant P123 as a template and the tetraethyl orthosilicate（TEOS）as the silicon source in an acidic environment.The spherical mesoporous material SBA-15 has the advantage of a large specific surface area,which can provide good dispersion for supporting metal phosphide and reduce agglomeration.（2）Using in-situ reduction method and sodium hypophosphite thermal decomposition method,ethylene glycol as solvent,SBA-15 as carrier,cobalt acetate tetrahydrate,nickel acetate tetrahydrate,indium nitrate,Gallium nitrate as metal sources to prepare catalysts,such as NiCo₂O₄@SBA-15,Co₃O₄@SBA-15,NiCoP@SBA-15,Co₂P@SBA-15,InP and GaP.Then these catalysts were characterized by various characterization methods such as XRD,SEM and TEM.The preparation conditions of single metal phosphide InP and GaP were explored,and InP and GaP were applied in the hydrolytic dehydrogenation studies of sodium borohydride.（3）The catalytic effects of NiCo₂O₄@SBA-15、Co₃O₄@SBA-15、NiCoP@SBA-15、Co₂P@SBA-15、InP and GaP catalysts on the catalytic hydrolytic dehydrogenation performance of sodium borohydride and ammonia borane were compared.It was found that the double metal phosphide NiCoP@SBA-15 had the best effect,followed by Co₂P@SBA-15.At 303 K and 308 K,and the sodium hydroxide concentration was fixed at 0.25M,the TOF values of NiCoP@SBA-15 catalyzed the hydrolysis of NH₃BH₃ were32.16 mol_（H2）·mol^-1_{（NiCoP@SBA-15）}·min^-11 and 38.88 mol mol_（H2）·mol^-1_{（NiCoP@SBA-15）}·min^-1,respectively.At 293 K,and the sodium hydroxide concentration was fixed at 1.0 M,the TOF value of NiCoP@SBA-15 catalyzed the hydrolysis of NaBH₄ was 8.18mol（H₂）·mol（NiCoP@SBA-15）^-1·min-1.At 303 K,and the sodium hydroxide concentration was fixed at 0.5 M,the TOF value of Co₂P@SBA-15 catalyzed the hydrolysis of NH₃BH₃ was 10.48mol（H₂）·mol（Co₂P@SBA-15）^-1·min-1.